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December 06, 2019, 10:40:17 AM

Author Topic: Wire lengths and mechanical connections  (Read 144 times)

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Offline mesamoo

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Wire lengths and mechanical connections
« on: July 29, 2019, 02:14:37 PM »
Hello all

I've begun my Stereomour II build and things seem to be going well so far :-)

This is my first electronics project in a long time, and perhaps I am too focused on minutia, but please bear with me.

I have 2 questions, one about the wire lengths given in the directions, and the other about mechanical connections before soldering.

First - wire lengths
I have reached the heater wiring stage (page 33-34) and have questions about the lengths of wire. It seems that the lengths of wire coming out of the sheath (of the shielded cable) are so short that the connection can barely be made (pt-8 pins 0 - 15, and the connections to the 9 pin sockets)

After shortening the red and black wires as described, the connections can be made, but there is so little wire coming out of the sheath that the wires have almost no slack (pt-8 pins 9 and 15).

In the images in the manual, these connections appear to have enough slack that they are at least not strained.

The wire coming out of the sheath to connect to the 9 pin sockets also seem precariously short. (9 pin socket pins c4-c9 and b5-b9) almost touch the other socket pins which seems like it will possibly lead to melting the covering of the wire and possible shorts when additional connections are made.

I know that in many cases wire length has been kept to a minimum to reduce noise. I am just curious what kinds of variations in length are acceptable. Are these lengths really supposed to be so short that the connection can barely be made? If there is an additional 1/2 inch of wire coming out of the sheath will it have a detrimental effect?

Second - mechanical connections before soldering
It is commonly said that, when soldering, the strength of (mechanical) wire connections should be solid (do not depend on the solder to hold the connection). This makes sense, so most of my connections have been quite strong even without solder (wrapping and pinching wherever possible.)

But, if my mechanical connections are too solid, do I risk increased difficulty when I later install the Shunt Regulator and or DC Filament Supply modifications.

Anyway I appreciate any input or clarification.

The 2 attached images show my connections, the first is the PT-8 with just a little relief (additional length) and the 9 pin sockets with an additional 1/4 to 1/2 inch of length. (Top of page 34 says cut 1/2 inch off of rd wires connecting to B5 and B9, I left the original length)
« Last Edit: July 29, 2019, 02:17:08 PM by mesamoo »

Online Paul Birkeland

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Re: Wire lengths and mechanical connections
« Reply #1 on: July 29, 2019, 03:58:27 PM »
First - wire lengths
I have reached the heater wiring stage (page 33-34) and have questions about the lengths of wire. It seems that the lengths of wire coming out of the sheath (of the shielded cable) are so short that the connection can barely be made (pt-8 pins 0 - 15, and the connections to the 9 pin sockets)
What I see in your photos in terms of wire lengths looks good.  I would put a little more solder onto those power transformer terminals though.  They also take a decent amount of heat to solder properly.

The wire coming out of the sheath to connect to the 9 pin sockets also seem precariously short. (9 pin socket pins c4-c9 and b5-b9) almost touch the other socket pins which seems like it will possibly lead to melting the covering of the wire and possible shorts when additional connections are made.
The 9 pin sockets in the Stereomour don't get particularly hot.  You can always press those wires down a bit so they are closer to the chassis plate.

I know that in many cases wire length has been kept to a minimum to reduce noise. I am just curious what kinds of variations in length are acceptable. Are these lengths really supposed to be so short that the connection can barely be made? If there is an additional 1/2 inch of wire coming out of the sheath will it have a detrimental effect?
A little extra length isn't the end of the world.  Extra stripped length of wire can lead to issues where the extra exposed wire touches things it shouldn't.

It is commonly said that, when soldering, the strength of (mechanical) wire connections should be solid (do not depend on the solder to hold the connection). This makes sense, so most of my connections have been quite strong even without solder (wrapping and pinching wherever possible.)

But, if my mechanical connections are too solid, do I risk increased difficulty when I later install the Shunt Regulator and or DC Filament Supply modifications.
You shouldn't have any issues.  For the upgrades, you can usually cut off what's no longer needed, then add the new parts.  I would not recommend doing more than half a wrap on anything though, as you can start filling up the space in a terminal too much to add other parts down the road.
Paul "PB" Birkeland

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Offline mesamoo

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Re: Wire lengths and mechanical connections
« Reply #2 on: July 29, 2019, 04:35:16 PM »
Hi Paul,

Thanks for the help,

Quote
What I see in your photos in terms of wire lengths looks good.  I would put a little more solder onto those power transformer terminals though.  They also take a decent amount of heat to solder properly.

I'm starting to get a bit more confident with my soldering, so I'll check the soldering on the connections I've completed especially the transformers.

Quote
A little extra length isn't the end of the world.  Extra stripped length of wire can lead to issues where the extra exposed wire touches things it shouldn't.

My concern was more about the length of wire extending from the section of removed  sheath, not about how much to strip for soldering. (I am pretty comfortable with the 1/4" stripped wire for solder connections). It sounds like having a little more wire (1/4" to 1/2") extending from the sheath as I did around the 9 pin sockets is not a big issue.

Quote
I would not recommend doing more than half a wrap on anything though, as you can start filling up the space in a terminal too much to add other parts down the road.

Sounds good, I was really pleased that some of my wraps turned out so snug until I started thinking about upgrades, I will stick to half a wrap.

Thanks again for the help